The Treasury Department auctioned $40 billion in three-month bills at a discount rate of 0.335 percent, the same as last week. Another $36 billion in six-month bills was auctioned at a discount rate of 0.470 percent, down from 0.480 percent last week.

The discount rates reflect that the bills sell for less than face value. For a $10,000 bill, the three-month price was $9,991.53, while a six-month bill sold for $9,976.24. That would equal an annualized rate of 0.34 percent for the three-month bills and 0.478 percent for the six-month bills.

Separately, the Federal Reserve said Tuesday that the average yield for one-year Treasury bills, a popular index for making changes in adjustable rate mortgages, rose to 0.61 percent last week from 0.59 percent the previous week.